This invention relates to a radiation image capturing apparatus for use in X-ray mammography, the radiographing of a chest or bones of limbs, etc., for example.
For a system for use in radiography for medical diagnosis, an image forming system, in which a silver halide photographic film is brought in close contact with a fluorescent intensifying screen, exposed to an X-ray image, developed by an automatic developing apparatus, fixed, rinsed, and dried, has been heretofore used generally.
In such an X-ray image diagnosis for medical use or a non-destructive inspection, what is called an X-ray film using a silver halide emulsion has been broadly used. Especially in image diagnosis for medical use, a screen film system having a intensifying screen and an X-ray film in combination has been used for about one hundred years.
Such image information is what is called analogue image information, therefore it is not possible to make such arbitrary image processing or instantaneous electrical transmission as has been done in digital image information processing which has been continuously developed in recent years.
Computed radiography (CR) as a digital technology for an X-ray image is now accepted in medical fields. However, its image sharpness is insufficient and spatial resolution is also insufficient, therefore, it has not attained an image quality level of the screen film system. Further, as a new digital X-ray imaging system, it has been developed a flat-panel X-ray detecting device (FPD) using thin film transistors (TFT) described in, for example, John Rowlands: xe2x80x9cAmorphous Semiconductors Usher in Digital X-ray Imagingxe2x80x9d Physics Today, November 1997, p. 24, L. E. Antonuk: xe2x80x9cDevelopment of a High Resolution, Active Matrix, Flat-Panel Imager with Enhanced Fill Factorxe2x80x9d, SPIE, vol. 3032, p. 2, (1997), etc.
This has the advantage that its apparatus is made more small-sized than CR and its image quality is excellent. However, on the other hand, it has the defects that an enormous expense and a long period is necessary in newly developing an FPD using thin film transistors (TFT), and that, from the viewpoint of the manufacturing technology and the S/N ratio of the image obtained, it is difficult to make the pixel size small, which makes the resolution of the image low as 3-4 lp/mm or so.
If a radiation image can be obtained by using a number of low-priced area sensors such as CCD or CMOS sensors, the reliability as a sensor is high, the manufacturing cost can be reduced, and resolution of the image can be easily raised.
Incidentally, in order to obtain an image by an FPD, it is necessary such correction of the signal value as is represented by offset correction and gain correction; first, the signal value of each pixel when it is not exposed to a radiation and the signal value when it is exposed to a uniform radiation which has not been transmitted through the object of radiographing are obtained, to obtain image data for correction (correction data). This operation is generally called calibration. In an FPD using a number of area sensors, it is necessary to combine images which have been obtained by the respective area sensors; therefore, on top of the above-described correction of the signal value, geometrical corrections such as parallel shift, rotation, and a correction of distortion become necessary. For these geometrical corrections, it is necessary that the condition of the mounting of each area sensor and the lens unit can cope with the variation with the passage of time and the variation owing to environmental temperature, vibration, impact, etc; therefore, they are more complex than a mere correction of a signal value, and in most cases, because an error in the corrections makes a great hindrance in diagnosis, the corrections must be carried out more reliably than the correction of a signal value. Further, in order to carry out the combination of images in the case where a number of area sensors are used precisely in a practically short time, it has been necessary to grasp the positional relation of the sensors precisely.
This invention has been done in view of the above-described actual circumstances, and it is an object of the invention to provide a radiation image capturing apparatus which has a high reliability by calibration, and is capable of being subjected to the reduction of manufacturing cost, raising the resolution of the image easily, and being made flat-shaped and of light weight.
In order to solve the above-described problems and accomplish the object, this invention has any one of the structures described below.
(1) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order, further comprising a calibration practicing means for obtaining image data for correction by automatically carrying out calibration after a certain time from the turning-on of the electric power source, and a memory means for memorizing image data for correction obtained by calibration.
According to the invention described in this paragraph (1), image data for correction can be obtained by automatically carrying out calibration after a certain time from the turning-on of the electric power source; therefore, the apparatus has a high reliability and the resolution of the image can be easily raised.
(2) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order, further comprising a calibration practicing means for obtaining image data for correction by automatically carrying out calibration after passage of a certain time from the former calibration while the electric power source is kept turned on, and a memory means for memorizing image data for correction obtained by calibration.
According to the invention described in this paragraph (2), calibration can be automatically carried out when a certain set time has passed with the timer counting from the former calibration while the electric power source is kept turned on; therefore, the apparatus has a high reliability and the resolution of the image can be easily raised.
(3) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order and comprising a means for counting the cumulative number of times of image capturing, further comprising a calibration practicing means for obtaining image data for correction by automatically carrying out calibration when the number of times of image capturing from the former calibration has reached a specified number of times, and a memory means for memorizing image data for correction obtained by calibration.
According to the invention described in this paragraph (3), calibration can be automatically carried out when the number of times of image capturing from the former calibration has reached the specified number of times with a counter counting the number of times of image capturing; therefore, the apparatus has a high reliability and the resolution of the image can be easily raised.
(4) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order, further comprising a calibration specifying means for specifying the method and/or the timing of calibration.
According to the invention described in this paragraph (4), the method and/or the timing of calibration can be specified and an operator can arbitrarily vary the method and/or the timing of calibration in accordance with, for example, the operational condition of the radiation image capturing apparatus.
(5) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (4), further comprising an captured-image-processing preferring means for carrying out calibration in the case where image capturing or captured-image-processing has already started at the predetermined time for calibration, after the image capturing or the captured-image-processing has been completed.
According to the invention described in this paragraph (5), in the case where image capturing or captured-image-processing has started at the predetermined time for calibration, calibration is carried out after the image capturing or captured-image-processing has been completed, therefore, image capturing or captured-image-processing is never interrupted.
(6) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order, further comprising a calibration start operating means for starting calibration at an arbitrary timing.
According to the invention described in this paragraph (6), by starting calibration at an arbitrary timing, calibration can be started at an arbitrary timing, for example, in accordance with the operational condition of the radiation image capturing apparatus.
(7) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (6), further comprising an alarm means for warning, during calibration, that the apparatus is in process of calibration.
According to the invention described in this paragraph (7), it is possible to warn, during calibration, that the apparatus is in process of calibration, and to notify that the apparatus is in process of calibration by an alarm display or a buzzer.
(8) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (7), further comprising an image capturing forbidding warning means for urging the stop of start of image capturing or captured-image-processing during calibration.
According to the invention described in this paragraph (8), calibration can be preferred by urging the stop of start of image capturing or captured-image-processing during calibration.
(9) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (8), further comprising an image capturing forbidding means for forbidding image capturing or captured-image-processing during calibration.
According to the invention described in this paragraph (9), image capturing or captured-image-processing is forbidden during calibration, and for example, even when the image capturing start switch is pressed, the start of image capturing or captured-image-processing can not be carried out.
(10) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (7), further comprising image capturing wedging means for interrupting calibration and wedging image capturing into it using correction data immediately before it for the captured-image-processing, in the case where a request for image capturing or captured-image-processing is made during calibration.
According to the invention described in this paragraph (10), in the case where a request for image capturing or captured-image-processing is made during calibration, calibration is interrupted and image capturing is wedged into it; therefore the apparatus can cope with the case where it is necessary to prefer to do image capturing or captured-image-processing immediately, for example, as an urgent measure.
(11) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (10), further comprising plural sets of correction data.
According to the invention described in this paragraph (11), the plural sets of correction data obtained by a plurality of times of calibration are memorized, and they can be used selectively at need.
(12) A radiation image capturing apparatus as set forth in the paragraph (11), wherein the latest correction data are preferentially used in captured-image-processing.
According to the invention described in this paragraph (12), by using preferentially the latest correction data in captured-image-processing, correction and combination of images can be more precisely carried out and the resolution of the image can be raised easily.
(13) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (11), wherein correction data which are renewed in such a manner as to always include the latest data are memorized.
According to the invention described in this paragraph (13), by memorizing correction data which are renewed in such a manner as to always include the latest data, the latest correction data are certainly memorized even though the information volume of the memorized correction data reaches nearly to the limit of the memory capacity of the memory means; therefore, it is possible to make the apparatus use the latest correction data in captured-image-processing. (14) A radiation image cap turing apparatus as set forth in any one of the paragraphs (1) to (13), wherein at least one of correction data and original image data are memorized together with image data after correction as a set.
According to the invention described in this paragraph (14), because at least one of correction data and original image data is memorized together with image data after correction as a set, image data after correction and at least one of the correction data used in correction and the corresponding original image data can be approached simply and certainly, and the condition of the radiation image capturing apparatus at the time of image capturing can be known simply and certainly.
(15) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (14), further comprising discriminating information for correction data and original data corresponding to each other as incidental information to image data after correction.
According to the invention described in this paragraph (15), the apparatus comprises discriminating information for correction data and original image data corresponding to each other as incidental information to image data after correction; therefore, correction data and original image data corresponding to each other can be discriminated simply and certainly from the incidental information, and the condition of the radiation image capturing apparatus at the time of photographing can be known simply and certainly.
(16) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (15), further comprising correction data production judging means for judging if correction data have been produced and correction data non-use warning means for issuing a warning in the case where correction data have not been produced.
According to the invention described in this paragraph (16), by issuing a warning in the case where correction data have not been produced for the reason, for example, such as that the area sensors have not functioned at the time of calibration, that X-rays have not been applied to the object, or that correction data are not memorized in the memory means, calibration can be carried out again.
(17) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (15), further comprising correction data production judging means for judging if making a correction by the correction data is suitable and correction data non-use warning means for issuing a warning in the case where making a correction is not suitable.
According to the invention described in this paragraph (17), by judging if to make correction by the correction data is suitable and issuing a warning in the unsuitable case, calibration can be carried out again.
(18) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (17), said radiation image capturing apparatus being capable of outputting the image of at least one of correction data and original image data.
According to the invention described in this paragraph (18), it is possible to output the image of at least one of correction data and original image data onto a sheet of the transparent type or of the reflection type by a laser exposure apparatus of the scanning type, an ink jet printer, or the like, or onto a display device such as a CRT, or liquid crystal display; therefore, the condition of the radiation image capturing apparatus at the time of image capturing can be known easily and certainly.
(19) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (18), said radiation image capturing apparatus being capable of outputting the image of at least one of correction data and original image data together with the image of data after correction.
According to the invention described in this paragraph (19), it is possible to output the image of at least one of correction data and original image data together with the image of data after correction onto a sheet of the transparent type or of the reflection type by a laser exposure apparatus of the scanning type, an ink jet printer, or the like, or onto a display device such as a CRT, or liquid crystal display; therefore, the condition of the radiation image capturing apparatus at the time of photographing can be known easily and certainly, and further, by referring to the both images for comparison, more precise observation and diagnosis can be made.
(20) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (19), said radiation image capturing apparatus being capable of specifying which one or two is to be displayed out of correction data, original image data, and data after correction by a control means.
According to the invention described in this paragraph (20), by displaying any one or two of correction data, original image data, and data after correction, the condition of the radiation image capturing apparatus at the time of image capturing can be known easily and certainly, and further, by referring to the both images for comparison, more precise observation and diagnosis can be made.
(21) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (20), said radiation image capturing apparatus being capable of displaying the information of a defective pixel detected by calibration for data after correction.
According to the invention described in this paragraph (21), by displaying the information of a defective pixel detected by calibration, the condition of the radiation image capturing apparatus at the time of image capturing can be known easily and certainly, and further, more precise observation and diagnosis can be made.
(22) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (21), said radiation image capturing apparatus carrying out calibration with a higher resolution than the reading of an image at the time of image capturing.
According to the invention described in this paragraph (22), by carrying out calibration with a higher resolution than the reading of an image at the time of image capturing, more precise correction data can be obtained.
(23) A radiation image capturing apparatus as set forth in the paragraph (22), wherein correction data which are produced with a higher resolution than the reading of an image are used for geometrical corrections such as parallel shift, rotation, and a correction of distortion, and correction data which are produced by using data obtained for pixels with the additional ones to pixel size at the time of the reading of an image are used for signal value corrections such as an offset correction and a gain correction.
According to the invention described in this paragraph (23), by obtaining correction data by calibration, the apparatus has a high reliability and the resolution of the image can be easily raised.
(24) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (23), said radiation image capturing apparatus carrying out geometrical corrections after making signal value corrections.
According to the invention described in this paragraph (24), by obtaining correction data through carrying out geometrical corrections after making signal value corrections, the apparatus has a high reliability and the resolution of the image can be easily raised.
(25) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (23), said radiation image capturing apparatus carrying out signal value corrections after making geometrical corrections.
According to the invention described in this paragraph (25), by obtaining correction data through carrying out signal value corrections after making geometrical corrections, the apparatus has a high reliability and the resolution of the image can be easily raised.
(26) A radiation image capturing apparatus as set forth in any one of the paragraphs (1) to (25), wherein geometrical corrections are corrections in which affine transformations such as shift, rotation, enlargement, and reduction is carried out after making a correction of distortion.
According to the invention described in this paragraph (26), geometrical corrections are corrections in which affine transformations such as parallel shift, rotation, enlargement, and reduction is carried out after making a correction of distortion, and by obtaining correction data in this way, the apparatus has a high reliability and the resolution of the image can be easily raised.
(27) A radiation image capturing apparatus as set forth in the paragraph (25), said radiation image capturing apparatus, in the case where only signal value corrections are made as calibration, carrying out geometrical corrections using the latest correction data, and after that, carrying out calibration in order to obtain correction data for making only signal value corrections, and carrying out signal value corrections only using data for signal value corrections obtained by the calibration.
According to the invention described in this paragraph (27), in the case where only signal value corrections are made as calibration, geometrical corrections are carried out using the latest correction data, after that, calibration is carried out in order to obtain correction data for making only signal value corrections, and signal value corrections only are carried out using data for signal value corrections obtained by the calibration, to obtain correction data; therefore, the apparatus has a high reliability and the resolution of the image can be easily raised.
(28) A radiation image capturing apparatus provided with a radiation image detector having a structure in which a scintillator, a lens unit array, and area sensors corresponding to each lens unit of the lens unit array are arranged in this order, wherein calibration is carried out using a repetition pattern provided outside the sensor area.
According to the invention described in this paragraph (28), calibration is carried out using a repetition pattern; therefore, with a simple structure, precise correction data can be obtained.
(29) A radiation image capturing apparatus as set forth in the paragraph (28), wherein the aforesaid repetition pattern is approximately of equal interval.
According to the invention described in this paragraph (29), the repetition pattern is approximately of equal interval; therefore, precise correction data can be obtained.
(30) A radiation image capturing apparatus as set forth in the paragraph (28) or (29), wherein the aforesaid repetition pattern is corresponding to the arrangement of the area sensors.
According to the invention described in this paragraph (30), the repetition pattern is corresponding to the arrangement of the area sensors; therefore, precise correction data can be obtained.
(31) A radiation image capturing apparatus as set forth in any one of the paragraphs (28) to (30), wherein the aforesaid repetition pattern is disposed at the X-ray source side on the outer flat plane portion of the radiation image detector.
According to the invention described in this paragraph (31), correction data can be obtained through calibrating the whole of the radiation image detector.
(32) A radiation image capturing apparatus as set forth in the paragraph (31), wherein the aforesaid repetition pattern is made of an X-ray intercepting substance.
According to the invention described in this paragraph (32), the repetition pattern is made of an X-ray intercepting substance; therefore, correction data can be obtained from a precise and distinct repetition pattern.
(33) A radiation image capturing apparatus as set forth in any one of the paragraphs (28) to (30), wherein the aforesaid repetition pattern is disposed adjacent to the scintillator at the reverse side to the area sensors inside the radiation image detector.
According to the invention described in this paragraph (33), because the repetition pattern is disposed inside the radiation image detector, it is easy to keep the positional relation to the lens units or to the area sensors always in the same condition; therefore, precise correction data with a high reproducibility can be obtained.
(34) A radiation image capturing apparatus as set forth in the paragraph (33), wherein the aforesaid repetition pattern is made of an X-ray intercepting substance.
According to the invention described in the paragraph (34), the repetition pattern is made of an X-ray intercepting substance; therefore, correction data can be obtained from a precise and distinct repetition pattern.
(35) A radiation image capturing apparatus as set forth in any one of the paragraphs (28) to (30), wherein the aforesaid repetition pattern is disposed between the scintillator and the area sensors.
According to the invention described in the paragraph (35), because the repetition pattern is disposed inside the radiation image detector, it is easy to keep the positional relation to the lens units or to the area sensors always in the same condition; therefore, precise correction data with a high reproducibility can be obtained.
(36) A radiation image capturing apparatus as set forth in the paragraph (35), wherein the aforesaid repetition pattern is disposed on the surface at the area sensor side of the scintillator.
According to the invention described in the paragraph (36), a distinct image of the repetition pattern produced by the fluorescence of the scintillator can be utilized in calibration; therefore, more precise correction data can be obtained.
(37) A radiation image capturing apparatus as set forth in the paragraph (35), wherein the aforesaid repetition pattern is positioned on the surface of a transparent member which is disposed between the scintillator and the area sensors, said surface of a transparent member facing the scintillator.
According to the invention described in the paragraph (37), a distinct image of the repetition pattern produced by the fluorescence of the scintillator can be utilized in calibration; therefore, more precise correction data can be obtained.
(38) A radiation image capturing apparatus as set forth in the paragraph (37), wherein the aforesaid transparent member is a glass plate.
According to the invention described in the paragraph (38), the transparent member is a glass plate and of low cost, and further, because a glass plate has a high stiffness, precise correction data with a high reproducibility can be obtained.
(39) A radiation image capturing apparatus as set forth in any one of the paragraphs (35) to (38), wherein the aforesaid repetition pattern is formed of a light intercepting material.
According to the invention described in the paragraph (39), the repetition pattern is formed of a light intercepting material; therefore, correction data can be obtained from a precise and distinct repetition pattern.
(40) A radiation image capturing apparatus as set forth in any one of the paragraphs (35) to (39), wherein at least a part of the repetition pattern is positioned at the overlapping portion of the sensing areas of the neighboring two area sensors.
According to the invention described in the paragraph (40), because at least a part of the repetition pattern is positioned at the overlapping portion of the sensing areas of the neighboring two area sensors and captured commonly by the two area sensors, the mutual positional relation of the neighboring two area sensors can be known precisely; therefore, precise correction data for the overlapping portion of the image area can be obtained.
(41) A radiation image capturing apparatus as set forth in any one of the paragraphs (28) to (40), wherein the aforesaid repetition pattern is dot-shaped.
According to the invention described in the paragraph (41), the repetition pattern is dot-shaped; therefore, precise correction data can be obtained.
(42) A radiation image capturing apparatus as set forth in any one of the paragraphs (28) to (40), wherein the aforesaid repetition pattern is line-shaped.
According to the invention described in the paragraph (42), the repetition pattern is line-shaped; therefore, precise correction data can be obtained.
(43) A radiation image capturing apparatus as set forth in any one of the paragraphs (28) to (42), wherein the line width of the aforesaid repetition pattern is 3 pixels or less on the final output image.
According to the invention described in the paragraph (43), the line width of the aforesaid repetition pattern is 3 pixels or less on the final output image; therefore, precise correction data can be obtained.
(44) A radiation image capturing apparatus as set forth in any one of the paragraphs (28) to (43), wherein, in the case where the magnitude of the signal value of the pixels corresponding to the repetition pattern is lowered to a half or less of the signal value for no repetition pattern being provided, the signal value of the pixels corresponding to the repetition pattern is interpolated by using the information of the signal value of the surrounding pixels.
According to the invention described in the paragraph (44), in the case where the magnitude of the signal value of the pixels corresponding to the repetition pattern is lowered to a half or less of the signal value for no repetition pattern being provided, the signal value of the pixels corresponding to the repetition pattern is interpolated by using the information of the signal value of the surrounding pixels; therefore precise correction data can be obtained.
(45) A radiation image capturing apparatus as set forth in any one of the paragraphs (28) to (44), wherein the aforesaid repetition pattern is capable of being attached and detached.
According to the invention described in the paragraph (45), the repetition pattern is capable of being attached and detached, and at the time of image capturing, by detaching the repetition pattern, its influence to the radiation image can be eliminated.
(46) A radiation image capturing apparatus as set forth in any one of the paragraphs (35) to (45), said radiation image capturing apparatus comprising a light source inside the radiation image detector, and making the light source turned on at the time of calibration.
According to the invention described in the paragraph (46), the light source is turned on at the time of calibration; therefore, precise correction data for geometrical corrections can be obtained without application of radiation rays.
(47) A radiation image capturing apparatus as set forth in the paragraph (46), wherein the aforesaid light source is made up of a plurality of point light sources.
According to the invention described in the paragraph (47), the light source is made up of a plurality of point light sources; therefore, precise correction data can be obtained.
(48) A radiation image capturing apparatus as set forth in the paragraph (47), wherein the aforesaid point light sources are LED""s.
According to the invention described in the paragraph (48), the point light sources are LED""s; therefore, it is possible to make the apparatus small-sized and of light weight.
(49) A radiation image capturing apparatus as set forth in the paragraph (47) or (48), wherein one or more point light sources are provided for each of the area sensors.
According to the invention described in the paragraph (49), because one or more point light sources are provided for each of the area sensors, it is possible to make the apparatus small-sized and of light weight, and sufficient light quantity is given to each sensor reliably; therefore, precise correction data can be obtained.
(50) A radiation image capturing apparatus as set forth in the paragraph (46), wherein light from the light source is applied from the side surface of the transparent member which is placed between the scintillator and the area sensors.
According to the invention described in the paragraph (50), because light from the light source is applied from the side surface of the transparent member which is placed between the scintillator and the area sensors, the light is transmitted through the transparent member and can illuminate a wide range; therefore, precise correction data can be obtained.
(51) A radiation image capturing apparatus as set forth in the paragraph (50), wherein the aforesaid transparent member is a diffuser plate and capable of being attached and detached.
According to the invention described in the paragraph (51), because the transparent member is a diffuser plate and light can be diffused to a wide range, precise correction data can be obtained; further, because the transparent member is capable of being attached and detached, it can be detached at the time of image capturing, which makes it possible to obtain a distinct radiation image.
(52) A radiation image capturing apparatus as set forth in any one of the paragraphs (47) to (51), wherein the aforesaid light from the light source is infrared rays, and the aforesaid repetition pattern is formed of a member which absorbs or reflects infrared rays and transmits visible light.
According to the invention described in the paragraph (52), the light from the light source is infrared rays, and the aforesaid repetition pattern is formed of a member which absorbs or reflects infrared rays and transmits visible light; therefore, a radiation image appearing as fluorescent light from the scintillator can be obtained without being influenced by the repetition pattern.
(53) A radiation image capturing apparatus as set forth in any one of the paragraphs (47) to (52), said radiation image capturing apparatus detecting the breakdown of the light source and making a display or warning.
According to the invention described in this paragraph (53), by detecting the breakdown of the light source and making a display or warning, the possibility of the breakdown of the light source during calibration is made extremely small.
(54) A radiation image capturing apparatus as set forth in the paragraph (53), said radiation image capturing apparatus being provided with a light source breakdown detecting means for detecting the breakdown of the light source at the time of actuating the electric power source.
According to the invention described in this paragraph (54), by detecting the breakdown of the light source at the time of actuating the electric power source, the possibility of the breakdown of the light source during calibration is made extremely small.
(55) A radiation image capturing apparatus which converts it into visible light by a scintillator, the information of an object of image capturing obtained by a radiation generated by a radiation generating means being transmitted through the object of image capturing, and further converts the visible light obtained by the conversion into an electrical signal through a lens unit or an array of lens units by an area sensor disposed at the position corresponding to said lens unit, to form a radiation image,
said radiation image capturing apparatus comprising position correcting means for correcting the positional deviation of pixels which is produced by the optical distortion produced by said lens unit and the positional deviation of said area sensor, a calibration chart for correcting a position provided at the surface of said scintillator or at a position equivalent to it, and a basic plane for disposing said calibration chart at a specified position with respect to the optical axis of the lens unit.
(56) A radiation image capturing apparatus as set forth in the paragraph (55), wherein the aforesaid calibration chart is disposed in a manner such that the positional deviation of the point on the calibration chart which is corresponding to the optical axis of the lens unit from the optical axis of the lens unit is equivalent to 5 pixels or less on the final output image.
(57) A radiation image capturing apparatus as set forth in the paragraph (56), wherein the aforesaid calibration chart is of point symmetry with respect to the point corresponding to the optical axis of the lens unit.
(58) A radiation image capturing apparatus as set forth in any one of the paragraphs (55) to (57), wherein the aforesaid calibration chart is lattice-shaped.
(59) A radiation image capturing apparatus as set forth in any one of the paragraphs (55) to (58), wherein the line width of the aforesaid calibration chart projected on the area sensor is smaller than 1 pixel of the area sensor.
(60) A radiation image capturing apparatus which converts it into visible light by a scintillator, the information of an object of image capturing obtained by a radiation generated by a radiation generating means being transmitted through the object of image capturing, and further converts the visible light obtained by the conversion into an electrical signal through a lens unit or an array of lens units by an area sensor disposed at the position corresponding to said lens unit, to form a radiation image,
said radiation image capturing apparatus comprising position correcting means for correcting the positional deviation of pixels which is produced by the optical distortion produced by said lens unit and the positional deviation of said area sensor, and a calibration chart for correcting a position provided at the surface of said scintillator or at a position equivalent to it, the area occupied by the image portion of said calibration chart being 3% or less of the whole image area.
(61) A radiation image capturing apparatus as set forth in the paragraph (60), wherein the area occupied by the image portion of the aforesaid calibration chart is 1% or less of the whole image area.
(62) A radiation image capturing apparatus which converts it into visible light by a scintillator, the information of an object of image capturing obtained by a radiation generated by a radiation generating means being transmitted through the object of image capturing, and further converts the visible light obtained by the conversion into an electrical signal through a lens unit or an array of lens units by an area sensor disposed at the position corresponding to said lens unit, to form a radiation image,
said radiation image capturing apparatus comprising a calibration chart for correcting a position provided at the surface of said scintillator or at a position equivalent to it, and position correcting means for correcting the positional deviation of pixels which is produced by the optical distortion produced by said lens unit and the positional deviation of said area sensor, wherein
the aforesaid position correcting means comprises position recognizing means for recognizing the specified position of said calibration chart, and correction value calculating means for calculating the correction values on the basis of the positional information obtained by said position recognizing means, and
by using the correction values obtained by said correction value calculating means, the image obtained by said area sensor is corrected.
(63) A radiation image capturing apparatus as set forth in the paragraph (62), wherein the aforesaid correction value calculating means calculates the correction values for the distortion aberration by the aforesaid lens unit on the basis of the positional information obtained by the aforesaid position recognizing means.
(64) A radiation image capturing apparatus as set forth in the paragraph (62), wherein the aforesaid correction value calculating means calculates the correction values of the position on the basis of the positional information obtained by the aforesaid position recognizing means.
(65) A radiation image capturing apparatus as set forth in the paragraph (62), wherein the aforesaid correction value calculating means calculates the difference in the size of images owing to the dispersion of the focal length of the lens units on the basis of the positional information obtained by the aforesaid position recognizing means.
(66) A radiation image capturing apparatus as set forth in any one of the paragraphs (62) to (65), wherein the aforesaid calibration chart is lattice-shaped, and the aforesaid position recognizing means recognizes intersecting points of the lattice as the specified positions of said calibration chart.
(67) A radiation image capturing apparatus as set forth in any one of the paragraphs (62) to (66), wherein the aforesaid correction value calculating means calculates correction values on the basis of the positional information obtained by the aforesaid position recognizing means, while it comprises correction value modifying means which carries out the correction of position with respect to one or plural basic points which are the same as or different from the aforesaid specified points recognized by said position recognizing means, and by evaluating the corrected position, modifies said correction values.
According to the invention described in the paragraph
(55), by comprising a calibration chart, the apparatus can correct the positional deviation of pixels with a high precision. Further, by providing a basic plane for disposing the calibration chart or a member on which the chart is drawn at the specified position with respect to the optical axis of the lens unit, it is possible to make the adjustment of the position for making the point on the calibration chart corresponding to the optical axis of the lens unit coincide with the optical axis of the lens unit at the enlargement side of the lens; therefore, the required accuracy can be made not so high as that in the adjustment of the position done on the area sensor, which makes easy the design and manufacturing of the apparatus.
According to the invention described in the paragraph (56), by suppressing it to be equivalent to 5 pixels or less, the positional deviation between the optical axis of the lens unit and the point of correspondence on the calibration chart to the optical axis of the lens unit, the correction of distortion aberration can be made with a high precision.
According to the invention described in the paragraph (57), by making the calibration chart of point symmetry with respect to the point of correspondence to the optical axis of the lens unit, it becomes easy to produce the data for correcting the distortion aberration.
According to the invention described in the paragraph (58), by making the calibration chart lattice-shaped, and letting one lattice indicate the area of one area sensor, the junction point in combining images obtained from neighboring area sensors can be easily recognized, and the images can be combined with a high precision.
According to the invention described in the paragraph (59), by making the line width of the lattice in the lattice-shaped calibration chart projected on the area sensor smaller than 1 pixel of the area sensor, it is possible to recognize the chart correctly with the ratio of intercepting the information of the original image suppressed to the minimum, which makes it possible to carry out the correction of the image obtained from each of the area sensors with a high precision.
According to the invention described in the paragraph (60), by making the structure be one such that the area occupied by the image portion of the calibration chart is 3% or less of the image area, the area intercepted by the chart is made small, which makes it possible to obtain an image which has a small number of image deficiencies and a high reliability.
According to the invention described in the paragraph (61), by making the structure be one such that the area occupied by the image portion of the calibration chart is 1% or less of the image area, the area intercepted by the chart is made smaller than the invention set forth in the paragraph (60), which makes it possible to obtain an image which has a smaller number of image deficiencies and a higher reliability.
According to the invention described in the paragraph (62), by obtaining the correction values with reference to the calibration chart, it is possible to make the correction of images obtained from each of the area sensors with a high precision.
According to the invention described in the paragraph (63), by obtaining the correction values with reference to the calibration chart, it is possible to correct the distortion aberration of the lens unit with a high precision.
According to the invention described in the paragraph (64), by obtaining the correction values with reference to the calibration chart, it is possible to correct the parallel shift or rotation of an image owing to the positional deviation of the disposed area sensor with a high precision.
According to the invention described in the paragraph (65), by obtaining the correction values with reference to the calibration chart, it is possible to correct the difference in the size of images owing to the dispersion of the lens units with a high precision.
According to the invention described in the paragraph (66), by making the calibration chart lattice-shaped, and recognizing the intersecting points of the lattice, it is possible to make the correction of images obtained from the respective area sensors with a high precision.
According to the invention described in the paragraph (67), by comprising correction value modifying means, the apparatus can makes the correction of images obtained from the respective area sensors with a very high precision.